I found this online (blook pressure association webpage), hope it answers some questions for you.
What should my blood pressure be?
140/90mmHg is the level of blood pressure used to diagnose high blood pressure. If your blood pressure is consistently raised at these levels and above, it will need to be treated. Treatment may involve making changes to your lifestyle and/or taking medication. This level of 140/90 mmHg is the level for high blood pressure for everyone, whether you are male or female, young or old.
High blood pressure can be a systolic reading of
140 or above, a diastolic reading of
90 or above, or both. For example, a reading of
150/85 mmHg is high because the systolic is above 140; a reading of 139/
95 mmHg is high because the diastolic is above 90. A reading of
150/95 mmHg is also high as both the systolic and the diastolic number are raised. As you get older you may find that your diastolic level is normal but your systolic level starts to rise and this is called
isolated systolic hypertension. This is common among older people, and still needs to be treated.
140/85 mmHg is the target blood pressure for people who are receiving treatment for their high blood pressure. The only exception to this target level is if you have diabetes, kidney disease or have already suffered a stroke or heart attack. Then it is worthwhile lowering your blood pressure even further and your doctor may as you to lower your blood pressure to 130/80 mmHg.
When you have your blood pressure measured, always ask what it is and keep a record if you can. By doing this you can see whether your blood pressure is stable or is increasing.